While our knowledge on regulation events is steadily increasing, we are much less informed about the functionality of individual regulation events and their quantitative relevance for controlling a given biological function and eventually a phenotype. For metabolism this function is the flux of small molecules that can be quantified network-wide through methods of 13C-flux analysis. This ability to quantify metabolic function allows us to investigate the question which of the multiple overlapping regulation mechanisms are employed by microbial cells to manage their small molecule traffic (1, 2). Even seemingly simple environmental adaptions typically lead to extensive transcriptional responses, although often only very few of these co-occurring regulation events are required for the specific adaptation (3). By combining various omics methods with computational analysis, we delineate regulation events that actively control metabolic flux coordination in microbes from the much larger number of co-occurring regulation events. The data strongly suggest that transcriptional regulation plays a much less important role in controlling pathway fluxes than previously thought because most enzymes are more abundant than necessary. Instead we find enzyme phosphorylation (4) and allosteric metabolite-enzyme interactions (5) to be much more important in controlling central metabolic fluxes.